Design, synthesis, in vitro, and in silico studies of 1,2,4-triazole-piperazine hybrid derivatives as potential MAO inhibitors

Probing N-substituted 4-(5-mercapto-4-ethyl-4H-1,2,4-triazol-3-yl)-N-phenylpiperdine-1-carboxamides as potent 15-LOX inhibitors supported with ADME, DFT calculations and molecular docking studies

In our continuous efforts to find out leads against the enzyme 15-lipoxygenase (15-LOX), the current study deals with the synthesis of a series of new N-alkyl/aralkyl/aryl derivatives of 2-(4-ethyl-5-(1-phenylcarbamoyl)piperidine-4H-1,2,4-triazol-3-ylthio)methylacetamide (7a-n) with anti-LOX activities. The synthesis was started by reacting phenylisocyanate with isonipecotate that sequentially converted into N-substituted ester (1), hydrazide (2), semicarbazide (3) and N-ethylated 5-(1-phenylcarbamoyl)piperidine-1,2,4-triazole (4). The final compounds, 7a-n, were obtained by reacting 4 with various N-alkyl/aralkyl/aryl electrophiles. Both the intermediates and target compounds were characterized by FTIR, 1H, 13C NMR spectroscopy, EI-MS and HR-EI-MS spectrometry and screened against soybean 15-LOX by chemiluminescence method. The eight compounds 7e, 7j, 7h, 7a, 7g, 7b, 7n, 7c showed potent inhibitory activities against 15-LOX with values ranging from IC50 0.36 ± 0.15 μM (7e) to IC50 6.75 ± 0.17 μM (7c) compared with the reference quercetin (IC50 4.86 ± 0.14 μM) and baicalein (IC50 2.24 ± 0.13 μM). Two analogues (7l, 7f) had significantly outstanding inhibitory potential with IC50 values 12.15 ± 0.23 μM and 15.54 ± 0.26 μM, whereas, the derivatives 7i, and 7d displayed IC50 values of 21.56 ± 0.27 μM, 23.59 ± 0.24 μM and the compounds 7k, 7m were found inactive. All analogues exhibited blood mononuclear cells (MNCs) viability >75 % at 0.25 mM concentration as determined by MTT method. Calculated pharmacokinetic properties projected good lipophilicity, bioavailability and drug-likeness properties and did not violate Lipinski's/Veber rule. Molecular docking studies revealed lower binding free energies of all the derivatives than the reference compounds. The binding free energies were -9.8 kcal/mol, -9.70 k/mol and -9.20 kcal/mol for 7j, 7h and 7e, respectively, compared with the standard quercetin (-8.47 kcal/mol) and baicalein (-8.98 kcal/mol). The docked ligands formed hydrogen bonds with the amino acid residues Gln598 (7e), Arg260, Val 126 (7h), Gln762, Gln574, Thr443, Arg580 (7j) while other hydrophobic interactions observed therein further stabilized the complexes. The results of density functional theory (DFT) revealed that analogues with more stabilized lower unoccupied molecular orbital (LUMO) had significant enzyme inhibitory activity. The data collectively supports these molecules as leads against 15-LOX and demand further investigations as anti-inflammatory agents.

Synthesis, in vitro, and in silico studies of new derivatives of diphenylpiperazine scaffold: A key substructure for MAO inhibition

Fifteen new diphenylpiperazine hybrids were designed, synthesized and in vitro biologically evaluated against hMAOs enzymes via fluorometric method. All of our new compounds displayed strong inhibitory activities against both two isoforms of hMAOs with IC50 range of 0.091-16.32 µM. According to selectivity index values, all hybrids showed higher selectivity against hMAO-A over hMAO-B. Compound 8 exhibited the best hMAO-A inhibition activity (IC50 value = 91 nM, SI = 19.55). With a selectivity index of 31.02 folds over MAO-B, compound 7 was revealed to be the most effective hMAO-A inhibitor. In silico prediction of physicochemical parameters and BBB permeability proved that all of the newly synthesized compounds have favorable pharmacokinetic profiles and acceptable ADME properties and can pass BBB. For clarification and explanation of the biological activity of compounds 7 and 8, molecular docking simulations were carried out. In light of this, 1,4-diphenylpiperazine analogues can be seen as an encouraging lead to develop safe and effective new drugs for treatment of many disorders such as anxiety and depression by inhibition of hMAO-A enzyme.

Piperazin incorporated Schiff Base derivatives: Assessment of in vitro biological activities, metabolic enzyme inhibition properties, and molecular docking calculations

The cytotoxic activities of the compounds were determined by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) method in human breast cancer (MCF-7), human cervical cancer (HeLa), and mouse fibroblast (L929) cell lines. The compounds MAAS-5 and four modified the supercoiled tertiary structure of pBR322 plasmid DNA. MAAS-5 showed the highest cytotoxic activity in HeLa, MCF-7, and L929 cells with IC50 values of 16.76 ± 3.22, 28.83 ± 5.61, and 2.18 ± 1.22 µM, respectively. MAAS-3 was found to have almost the lowest cytotoxic activities with the IC50 values of 93.17 ± 9.28, 181.07 ± 11.54, and 16.86 ± 6.42 µM in HeLa, MCF-7, and L929 cells respectively at 24 h. Moreover, the antiepileptic potentials of these compounds were investigated in this study. To this end, the effect of newly synthesized Schiff base derivatives on the enzyme activities of carbonic anhydrase I and II isozymes (human carbonic anhydrase [hCA] I and hCA II) was evaluated spectrophotometrically. The target compounds demonstrated high inhibitory activities compared with standard inhibitors with Ki values in the range of 4.54 ± 0.86-15.46 ± 8.65 nM for hCA I (Ki value for standard inhibitor =  12.08 ± 2.00 nM), 1.09 ± 0.32-29.94 ± 0.82 nM for hCA II (Ki value for standard inhibitor = 18.22 ± 4.90  nM). Finally, the activities of the compounds were compared with the Gaussian programme in the B3lyp, HF, M062X base sets with 6-31++G (d,p) levels. In addition, the activities of five compounds against various breast cancer proteins and hCA I and II were compared with molecular docking calculations. Also, absorption, distribution, metabolism, excretion, and toxicity analysis was performed to investigate the possibility of using five compounds as drug candidates.

Synthesis, characterization, DFT and molecular docking studies of acetone O-((2,5-dichlorophenyl)sulfonyl) oxime

Acetone O-((2,5-dichlorophenyl)sulfonyl) oxime was prepared from 2,5-dichlorophenylsulfonyl chloride and acetone oxime using triethylamine. The compound was characterized using 1H NMR and 13C NMR spectra. Molecular docking was performed with the compound and cholinesterase enzymes. The average affinity of the compound with the acetylcholinesterase and butyrylcholinesterase was calculated at −7.46 ± 0.14 and −6.70 ± 0.00 kcal/mol, respectively. The density functional theory method was also used to complement the experimental study. The findings of this work might be useful towards the applications of the compound studied.